Clutch pedal raises and drops

[Phatvalver]

Hi guys,
Im fairly new to the forum and would really appreciate some help as im at my wits end with my car....
So its a 55 reg mk5 gti 2.0 tfsi
The story goes..... I bought the car beggining of november and all was fine... Within a day i was getting a raise of clutch pedal when accelerating and a drop when letting off accelerator!
Had this diagnosed as slave cylinder (in gearbox)
But also at same place a conflicting diagnosis being the DMF was the cause pushing pressure back onto the slave making the travel in the pedal!
So the car stayed and i get a phone call its the master cylinder
They say there is fluid round it and its letting in air! Ok so £150 later the clutch feels great!
I use the car for 24 hrs and boom clutch pedal drops to the floor

[Phatvalver]

So i make the call and the response " you will have to pay again for a new one once the other issue is sorted thats caused the master to fail"
I dont use garages often as i can never trust who has control of my car, but on this occation it was more of a time thing for me!!
So i sat the car up for a week and decided im gonna do this myself with a lil help from my friends....
The long and short of it is i ordered 4 complete clutch kits including dmf from different suppliers 1 after the other and the all supplied the wrong kit! With much stress and this all being over christmas the car has sat on axle stands on my drive for well over a month....
I then turn to some specialists in the buisiness and call Alex from AKS tunning!!
Next day i have a full helix organic clutch kit and golf r dmf on my door step!
This was fitted last weekend, unfortunatly daylight got the better of me and my mates so we down tools

[Phatvalver]

Today i buy the new master, fitted within an hour which i expected to be a s**t of a job but was acctually very easy....we then bleed the system...
It bled up really well, we got a strong peddle and no air whatsoever!!
So then we test drive the car and yep you got it a raising and dropping pedal on acceleration and deaccelerating!!!
All components are new in the system
Im getting a power bleeder in the morning with the hope that will make a difference... But as it is im so close to giving up its untrue

[Phatvalver]

Any help would be much appreciated and sorry for the long story....

[Phatvalver]

Presure bled the system thiseve

[Ricky123]

Not sure if the pedal itself has a sort of master cylinder built in to it? I had an issue with a mk5 gti I owned once where the clutch pedal would fall to the floor over night so I had to lift it up on first use of the car in the morning and I'm sure I remember reading something about a cylinder in the pedal?

I could be wrong but worth a check.

Also may be worth trying to back bleed it

[Phatvalver]

Hi, yes ive changed the master which is attached to the peddle itself, i was going with a gravity bleed next and as you have said back bleeding is the next option beyond that...
If anybody thinks they can fix this im happy to pay good

[Phatvalver]

Hi guys, does anyone have experience of crankshaft end float?? Where starting to think this may be the cause of my pedal movement...
If so i will more than likely break the car

[doylebros]

Hi guys, does anyone have experience of crankshaft end float?? Where starting to think this may be the cause of my pedal movement...
If so i will more than likely break the car

Never had issues with end float causing this fault but anything is possible.
I had a strange fault which was cured by replacing the flexibile hose to the slave cylinder which was deforming and causing something similar to your fault so check that visually when the pedal is being pumped.

[Phatvalver]

Will do that mate thankyou, ile have a go at anything now..

[doylebros]

Keep this in mind (I've not but one of the lads changed this)
 http://www.parts-catalogs.info/volkswagen/en/?i=cat_vag_models&brand=vw&number=1714&set=1728&ein=2007&f=474&hauptgr=1234567890&hg=7&grf=072125409&bf=72125&hgug=721&ug=21&parent_id=2348357&detail_id=2348436

To fix a pedal not returning fault pipe with plastic chamber

[Phatvalver]

Nice one, thanks for that...
The plastic chamber is the clutch bias valve which apparently controlls the pressure applied to the slave/clutch.
I did question myself if this could be faulty...

[doylebros]

I'm Interested in how you progressed with this fault.

[Phatvalver]

Hi,
I tbh am about to break the car i think...
I have since pressure bled the system to which it never solved it
I have vacuum bled the system to which that never solved it
So i give up and take it to a well rated vw specialist in the area and he drives it 200 yards up the road!
He says its not a hydrolic issue its mechanical.
We have tested for end float in the crankshaft and its fine!
I have spoken to alex at aks today and he says it could be that the intermediate shaft in the gearbox has play as this is common for my age of box
And the shaft is moving in and out which is causing the pressure drop and gain...
Altho he is extremely knowledgable i have sat here thisafternoon trying to work out how that can give my symtoms as the shaft slides through the slave and applies no pressure to it??
I maywell be totally wrong here so im not going against his word atall.
I will endevour to remove the box and investigate.

[doylebros]

Why I ask we got one today pedal stuck to the floor (tried all sorts ) then they changed that pipe c/w valve and fixed it.